Electric piano construction



Aug. 19, 1941. w. L. DOUDEN ELECTRIC PIANO CONSTRUCTION Filed Dec. so,1958 Patented Aug; 19, 1941 ELECTRIC PIANO CONSTRUCTION William L.Douden, Philadelphia, Pa, assignorfto Radio Corporation of America, acorporation of Delaware Application December 30, 1938, Serial No.248,563

2 Claims.

This invention relates to the construction of electric pianos or pianosin which the vibration of the strings is electrically converted intosound, and pertains particularly to the frame construction of suchdevices.

In the prior art, it has been thought necessary to mount the bridge ofan electrical piano in such a manner that it could vibrate more or lessfreely or somewhat in the fashion of the vibration of the bridge of aconventional piano. Such a mounting of'the piano bridge has been foundunnecessary and, in fact, a comparatively rigid mounting of the bridgeis described and claimed in Demuths application Serial No. 237,001,filed October 26, 1938 (RCV D6348). The said Demuth application pointsout the advantages of rigid mounting of the bridge, such as greater timeof vibration of strings, etc. In the said Figure 1 is a rear view of apiano frame casting with the bridge and pickup units attached inaccordance with the invention, and

Figure 2 is a section taken along the line 22 of Figure 1.

The usual castiron piano frame is indicated at 10. The particular frameshown in the drawing is one adapted to use in the small upright type ofpianos. "This frame carries the usual wrest plank II which carries thetuning pins l3 connected to the strings l2. As shown in Figure 2, thestrings I! are supported by the bridge l5. This bridge, instead of beingsupported upon a sounding board as .in conventional piano construction,is supported directly upon the brackets i6 and H. Both the bracket l6and the bracket therefore, not adjustable in relation to the frame.

Demuth application, the bridge is shown and de- 1 scribed as mounted onmetal brackets secured-to the piano frame, and the mounting of magneticpickups is disclosed as being accomplished on somewhat similar brackets.

In the said Demuth construction, the frame andbracket assembly is moreor less built up. In a piano construction in accordance with the presentinvention, the brackets for supporting the bridge and also forsupportingthe electromagnetic pickups are cast integral with the pianoframe, in order to prevent any possibility of their vibration ordisplacement in relation to the piano frame. This arrangement not onlyaccomplishes all the results of the Demuth construction but, inaddition, it provides a predetermined fixed location for the bridge andfor the pickup units and positively precludes their subsequentdisplacement or disarrangement.-

One object of the invention'is to provide an improved pianoconstruction;

Another object of the invention is to provide a piano frame constructionofgreater rigidity than heretofore provided;

Another object of the invention is to provide a comparatively simple andinexpensive construction of an electric piano.

Another object of the invention is to provide means for positivelyholding the strings, bridge and electrical pickups of a piano inpredetermined fixed relation to each other;

Other and incidental objects 01' the invention will be apparent to thoseskilled inthe art from a reading of the following specification and aninspection of the accompanying drawing, in which The faces of thesebrackets toward the strings and bridge may, if desirable or necessary,be finished off uniformly by planing or milling their surfaces into asingle plane, but thisis usually unnecessary. The bridge i5 is as usualcomposed of one or more strips of hardwood and is firmly secured to thebrackets l6 and I1 by appropriate screws 20. It will be apparent that,due to the fact that the brackets I6 and I! are cast integral with theframe i0 and the bridge is secured firmly to these brackets, the bridgewill be incapable of any material vibration and, therefore, the energyof the vibrating strings will not be dissipated through the bridge.

The strip 18 supporting the pickup elements i9 may be mounted on thebrackets I6 and il in the same manner as the bridge IS. The pickupstrips i8 may be divided into as many sections as is convenient, asillustrated, for example, in Figure 1. Since these pickup strips aremounted rigidly upon the same brackets as the bridge i 5, it will beapparent that it will be substantially impossible for the pickups andthe bridge to get out of adjustment in relation to each other. Since thebridge l5 supports the strings I2 and the pickup strip. i8 is supportedby the bracket [8 near to the bridge ii, the relation between thepickups and the strings I! will be predetermined by the construction ofthe pickup strips and by the height of the bridge. The constructionprevents any tampering with the relation between the pickups and thestrings by persons tuning the piano or by others who may have occasionto handle the instrument. The pickups used are preferably of the typeshown and described in Demuth application Secent to and spaced from saidbridge and adja cent to the plane of strings supported by said bridge.

2. In a piano, a cast frame, bracket members integral with said frameand extending inwardly therefrom at spaced intervals, a bridge immovablyfixed to said bracket members for supporting piano strings, andelectrical pickup devices immovably supported on said bracket membersadjacent to and spaced from said bridge and adjacent to the plane ofstrings supported by said bridge.

WILLIAM L. DOUDEN.

